Cooling systems for cooling electric machines within electrified vehicles

ABSTRACT

This disclosure details cooling systems for cooling electric components, such as electric machines, within electrified vehicles. Exemplary cooling systems may include a spray bar positioned relative to a rear face of a stator of the electric machine. In some embodiments, the spray bar may be positioned axially between the rear face of the stator and a torque converter housing. One or more nozzles of the spray bar are configured to direct a coolant between adjacent back irons of the stator, onto end windings of the stator, or both. Actively cooling the stator allows the electric machine to operate at higher torques and speeds, thereby increasing performance.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. patent application Ser. No. 16/382,524,which was filed on Apr. 12, 2019.

TECHNICAL FIELD

This disclosure relates to cooling systems that include spray bars forcooling components within electrified vehicles.

BACKGROUND

The desire to reduce automotive fuel consumption and emissions has beenwell documented. Therefore, electrified vehicles are being developedthat reduce or completely eliminate reliance on internal combustionengines. In general, electrified vehicles differ from conventional motorvehicles because they are selectively driven by one or more batterypowered electric machines (e.g., electric motors). Conventional motorvehicles, by contrast, rely exclusively on the internal combustionengine to propel the vehicle. A high voltage traction battery packtypically powers the electric machines and other electrical loads of theelectrified vehicle.

Electric machines can generate a significant amount of heat whenoperating at low speed/high torque conditions. The functionality ofelectric machines may be limited if the generated heat is not activelymanaged.

SUMMARY

A transmission system according to an exemplary aspect of the presentdisclosure includes, among other things, an electric machine including arotor and a stator, and a spray bar positioned adjacent to a rear faceof the stator. A first nozzle of the spray bar is configured to direct acoolant between adjacent back irons of the stator, onto end windings ofthe stator, or both.

In a further non-limiting embodiment of the foregoing transmissionsystem, the spray bar is positioned axially between the rear face ofstator and a torque converter of the transmission system.

In a further non-limiting embodiment of either of the foregoingtransmission systems, the spray bar is located near a top edge of thestator that coincides with a twelve o'clock position of the stator inits mounted position within the transmission system.

In a further non-limiting embodiment of any of the foregoingtransmission systems, the spray bar includes a crescent shaped body.

In a further non-limiting embodiment of any of the foregoingtransmission systems, the spray bar covers between 60 degrees and 180degrees of the rear face of stator.

In a further non-limiting embodiment of any of the foregoingtransmission systems, the first nozzle is configured to direct thecoolant between the adjacent back irons of the stator, and a secondnozzle is configured to direct the coolant onto the end windings of thestator.

In a further non-limiting embodiment of any of the foregoingtransmission systems, the first nozzle includes a first orifice having afirst diameter and the second nozzle includes a second orifice having asecond diameter. The first diameter is larger than the second diameter.

In a further non-limiting embodiment of any of the foregoingtransmission systems, the spray bar is directly attached to the rearface of the stator.

In a further non-limiting embodiment of any of the foregoingtransmission systems, the spray bar includes a piloting surface receivedwithin a groove of the stator.

In a further non-limiting embodiment of any of the foregoingtransmission systems, the spray bar is suspended within an open spacedefined between the rear face of the stator and a torque converterhousing.

An electrified vehicle according to another exemplary aspect of thepresent disclosure includes, among other things, a front module at leastpartially housing an electric machine, a transmission gearbox aft of thefront module, a torque converter located axially between the frontmodule and the transmission gearbox, and a spray bar positioned axiallybetween a rear face of a stator of the electric machine and a housing ofthe torque converter.

In a further non-limiting embodiment of the foregoing electrifiedvehicle, a feed tube is connected to the front module by a firstmounting attachment and connected to the spray bar by a second mountingattachment.

In a further non-limiting embodiment of either of the foregoingelectrified vehicles, the feed tube is in fluid communication with acoolant passage formed in the front module at the first mountingattachment and is in fluid communication with a hollow section of thespray bar at the second mounting attachment.

In a further non-limiting embodiment of any of the foregoing electrifiedvehicles, the spray bar includes a crescent shaped body.

In a further non-limiting embodiment of any of the foregoing electrifiedvehicles, the spray bar covers between 60 degrees and 180 degrees of therear face of stator.

In a further non-limiting embodiment of any of the foregoing electrifiedvehicles, the spray bar is located near a top edge of the stator, andthe top edge coincides with a twelve o'clock position of the stator.

In a further non-limiting embodiment of any of the foregoing electrifiedvehicles, the spray bar includes a plurality of nozzles that protrudefrom a front face of the spray bar.

In a further non-limiting embodiment of any of the foregoing electrifiedvehicles, a first portion of the plurality of nozzles is configured todirect a coolant between adjacent back irons of the stator, and a secondportion of the plurality of nozzles is configured to direct the coolantonto end windings of the stator.

In a further non-limiting embodiment of any of the foregoing electrifiedvehicles, the first portion of the plurality of nozzles includes a firstorifice having a first diameter and the second portion of the pluralityof nozzles includes a second orifice having a second diameter. The firstdiameter is larger than the second diameter.

In a further non-limiting embodiment of any of the foregoing electrifiedvehicles, the spray bar is positioned relative to a top edge of thestator but not relative to a bottom edge of the stator.

The embodiments, examples, and alternatives of the preceding paragraphs,the claims, or the following description and drawings, including any oftheir various aspects or respective individual features, may be takenindependently or in any combination. Features described in connectionwith one embodiment are applicable to all embodiments, unless suchfeatures are incompatible.

The various features and advantages of this disclosure will becomeapparent to those skilled in the art from the following detaileddescription. The drawings that accompany the detailed description can bebriefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an exemplary powertrain of anelectrified vehicle.

FIG. 2 is a cross-sectional view of a transmission system of anelectrified vehicle.

FIG. 3 is a blown up view of a portion of the transmission system ofFIG. 2 .

FIG. 4 illustrates an exemplary cooling system for cooling an electricmachine of the transmission system of FIGS. 2-3 .

FIG. 5 illustrates an exemplary spray bar of the cooling system of FIG.4 .

FIG. 6 illustrates an exemplary connection between a spray bar and astator of an electric machine.

FIG. 7 illustrates an exemplary nozzle arrangement of a spray barpositioned for cooling an electric machine according to a firstembodiment of this disclosure.

FIG. 8 illustrates an exemplary nozzle arrangement of a spray barpositioned for cooling an electric machine according to a secondembodiment of this disclosure.

FIG. 9 illustrates an exemplary nozzle arrangement of a spray barpositioned for cooling an electric machine according to a thirdembodiment of this disclosure.

DETAILED DESCRIPTION

This disclosure details cooling systems for cooling electric components,such as electric machines, within electrified vehicles. Exemplarycooling systems may include a spray bar positioned relative to a rearface of a stator of the electric machine. In some embodiments, the spraybar may be positioned axially between the rear face of the stator and atorque converter housing. One or more nozzles of the spray bar areconfigured to direct a coolant between adjacent back irons of thestator, onto end windings of the stator, or both. Actively cooling thestator allows the electric machine to operate at higher torques andspeeds, thereby increasing the performance capabilities of the electricmachine. These and other features are discussed in greater detail in thefollowing paragraphs of this detailed description.

FIG. 1 schematically illustrates an electrified vehicle 10. Althoughillustrated as a hybrid electric vehicle (HEV) in some embodiments, thisdisclosure is applicable any type of electrified vehicle, including butnot limited to full hybrid electric vehicles (FHEVs), plug-in hybridelectric vehicles (PHEVs), and battery electric vehicles (BEVs). Inaddition, although a specific component relationship is illustrated inFIG. 1 , this illustration is not intended to limit this disclosure. Inother words, it should be readily understood that the placement andorientation of the various components of the electrified vehicle 10could vary within the scope of this disclosure.

The exemplary electrified vehicle 10 includes a powertrain 12. Thepowertrain 12 may include an engine 14 and a transmission system 16 thatis selectively driven by the engine 14. In an embodiment, thetransmission system 16 is a modular hybrid transmission (MHT). Thetransmission system 16 may include an electric machine 18 that ispowered by a high voltage battery pack 20, a torque converter 22, and amultiple-step ratio automatic transmission, or gearbox 24. In anembodiment, the electric machine 18 is configured as an electric motor.However, the electric machine 18 could alternatively be configured as agenerator or a combined motor/generator within the scope of thisdisclosure.

The engine 14 and the electric machine 18 may both be employed asavailable drive sources for propelling the electrified vehicle 10. Theengine 14 generally represents a power source that may include aninternal combustion engine such as a gasoline, diesel, or natural gaspowered engine, or a fuel cell. The engine 14 generates power andcorresponding torque that is supplied to the electric machine 18 when anengine disconnect clutch 26 that is disposed between the engine 14 andthe electric machine 18 is engaged.

In some embodiments, the engine 14 is started using the electric machine18 to rotate the engine 14 using torque provided through the enginedisconnect clutch 26. Alternatively, the electrified vehicle 10 may beequipped with a low voltage starter 54 operatively connected to theengine 14, for example, through a belt or gear drive. The starter 54 maybe used to provide torque to start the engine 14 without the addition oftorque from the electric machine 18. The starter 54 may be powered bythe high voltage battery pack 20, or the electrified vehicle 10 caninclude a low voltage battery 56 to provide power to the starter 54and/or other vehicle components.

The electric machine 18 may be any one of a plurality of types ofelectric machines. In an embodiment, the electric machine 18 is apermanent magnet synchronous motor.

When the engine disconnect clutch 26 is at least partially engaged,power flow from the engine 14 to the electric machine 18 or from theelectric machine 18 to the engine 14 is possible. For example, theengine disconnect clutch 26 may be engaged and the electric machine 18may operate as a generator to convert rotational energy provided by acrankshaft 30 and an electric machine shaft 32 into electrical energy tobe stored in the battery pack 20. The engine disconnect clutch 26 canalso be disengaged to isolate the engine 14 from the remainder of thepowertrain 12 such that the electric machine 18 can act as the solepower source for propelling the electrified vehicle 10.

The electric machine shaft 32 may extend through the electric machine18. The electric machine 18 is continuously drivably connected to theelectric machine shaft 32, whereas the engine 14 is drivably connectedto the electric machine shaft 32 only when the engine disconnect clutch26 is at least partially engaged.

The electric machine 18 is connected to the torque converter 22 via theelectric machine shaft 32. The torque converter 22 is thereforeconnected to the engine 14 when the engine disconnect clutch 26 is atleast partially engaged. The torque converter 22 includes an impellerfixed to the electric machine shaft 32 and a turbine fixed to atransmission input shaft 34. The torque converter 22 thus provides ahydraulic coupling between the electric machine shaft 32 and thetransmission input shaft 34.

The torque converter 22 is adapted to transmit power from the impellerto the turbine when the impeller rotates faster than the turbine. Themagnitude of the turbine torque and impeller torque generally dependupon the relative speeds. When the ratio of impeller speed to turbinespeed is sufficiently high, the turbine torque is a multiple of theimpeller torque. A torque converter bypass clutch 36 may also beprovided. When engaged, the torque converter bypass clutch 36frictionally or mechanically couples the impeller and the turbine of thetorque converter 22 to enable a more efficient power transfer. Thetorque converter bypass clutch 36 may be operated as a launch clutch toprovide smooth vehicle launch. Alternatively, or in combination, alaunch clutch similar to the engine disconnect clutch 26 may be providedbetween the electric machine 18 and the transmission gearbox 24 forapplications that do not include a torque converter 22 or a torqueconverter bypass clutch 36. In some embodiments, the engine disconnectclutch 26 is generally referred to as an upstream clutch and the torqueconverter bypass clutch 36 (which may be a launch clutch) is generallyreferred to as a downstream clutch.

The transmission gearbox 24 may include gear sets (not shown) that areselectively operated using different gear ratios by selective engagementof friction elements such as clutches, planetary gears, and brakes (notshown) to establish the desired multiple discrete or step drive ratios.The friction elements are controllable through a shift schedule thatconnects and disconnects certain elements of the gear sets to controlthe ratio between a transmission output shaft 38 and the transmissioninput shaft 34. The transmission gearbox 24 may be automatically shiftedfrom one ratio to another based on various vehicle and ambient operatingconditions by an associated controller. The transmission gearbox 24 thenprovides powertrain output torque to the transmission output shaft 38.

It should be understood that the hydraulically controlled transmissiongearbox 24 used with the torque converter 22 is but a non-limitingembodiment of a gearbox or transmission arrangement and that anymultiple ratio gearbox that accepts input torque(s) from an engineand/or a motor and then provides torque to an output shaft at thedifferent ratios is acceptable for use with the embodiments of thisdisclosure. For example, the transmission gearbox 24 may be implementedby an automated mechanical (or manual) transmission (AMT) that includesone or more servo motors to translate/rotate shift forks along a shiftrail to select a desired gear ratio. As generally understood by those ofordinary skill in the art, an AMT may be used in applications withhigher torque requirements, for example.

The transmission output shaft 38 may be connected to a differential 42.The differential 42 may also be referred to as a final drive. Thedifferential 42 drives a pair of wheels 44 via respective axles 46 thatare connected to the differential 42. In an embodiment, the differential42 transmits approximately equal torque to each wheel 44 whilepermitting slight speed differences, such as when the vehicle turns acorner. Different types of differentials or similar devices may be usedto distribute torque from the powertrain 12 to one or more of the wheels44. In some applications, torque distribution may vary depending on theparticular operating mode or condition, for example.

Pressurized fluid for the transmission system 16 may be provided by atransmission pump 50. The transmission pump 50 may be connected to oradjacent to the electric machine 18 such that it rotates with theelectric machine 18 and the electric machine shaft 32 to pressurize andprovide sufficient line pressure for full operation of the transmissiongearbox 24. When the portion of the electric machine shaft 32 containingthe transmission pump 50 is at rest, the transmission pump 50 is also atrest and is inactive.

In order to provide pressurized transmission fluid when the transmissionpump 50 is inactive, an auxiliary pump 52 can also be provided. Theauxiliary pump 52 may be electrically powered, for example by the lowvoltage battery 56. In some embodiments, the auxiliary pump 52 providesa portion of the transmission fluid for the transmission gearbox 24 suchthat the transmission gearbox 24 is limited in operation, for example tocertain actuators or gearing ratios, when the auxiliary pump 52 isoperating.

Cooled transmission fluid, such as oil, may settle in a sump 58 from thetorque converter 22. The auxiliary pump 52 may pump transmission fluidfrom the sump 58 to the transmission pump 50 during certain conditions.

The powertrain 12 may additionally include an associated control unit40. While schematically illustrated as a single controller, the controlunit 40 may be part of a larger control system and may be controlled byvarious other controllers throughout the electrified vehicle 10, such asa vehicle system controller (VSC) that includes a powertrain controlunit, a transmission control unit, an engine control unit, etc. Itshould therefore be understood that the control unit 40 and one or moreother controllers can collectively be referred to as a “control unit”that controls, such as through a plurality of interrelated algorithms,various actuators in response to signals from various sensors to controlfunctions such as starting/stopping the engine 14, operating theelectric machine 18 to provide wheel torque or charge the battery pack20, selecting or scheduling transmission shifts, actuating the enginedisconnect clutch 26, etc. In an embodiment, the various controllersthat make up the VSC may communicate with one another using a common busprotocol (e.g., CAN).

The control unit 40 may include a microprocessor or central processingunit (CPU) in communication with various types of computer readablestorage devices or media. Computer readable storage devices or media mayinclude volatile and nonvolatile storage in read-only memory (ROM),random-access memory (RAM), and keep-alive memory (KAM), for example.KAM is a persistent or nonvolatile memory that may be used to storevarious operating variables while the CPU is powered down.Computer-readable storage devices or media may be implemented using anyof a number of known memory devices such as PROMs (programmableread-only memory), EPROMs (electrically PROM), EEPROMs (electricallyerasable PROM), flash memory, or any other electric, magnetic, optical,or combination memory devices capable of storing data, some of whichrepresent executable instructions, used by the controller in controllingthe engine or vehicle.

The control unit 40 may also communicate with various engine/vehiclesensors and actuators via an input/output (I/O) interface that may beimplemented as a single integrated interface that provides various rawdata or signal conditioning, processing, and/or conversion,short-circuit protection, and the like. Alternatively, one or morededicated hardware or firmware chips may be used to condition andprocess particular signals before being supplied to the CPU.

As schematically illustrated in FIG. 1 , the control unit 40 maycommunicate signals to and/or from the engine 14, the engine disconnectclutch 26, the electric machine 18, the torque converter bypass clutch36, the transmission gearbox 24, and/or other components. Although notexplicitly illustrated, those of ordinary skill in the art willrecognize various functions or components that may be controlled by thecontrol unit 40 within each of the subsystems identified above.Representative examples of parameters, systems, and/or components thatmay be directly or indirectly actuated using control logic executed bythe controller include fuel injection timing, rate, and duration,throttle valve position, spark plug ignition timing (for spark-ignitionengines), intake/exhaust valve timing and duration, front-end accessorydrive (FEAD) components such as an alternator, air conditioningcompressor, battery charging, regenerative braking, M/G operation,clutch pressures for engine disconnect clutch 26, torque converterbypass clutch 36, and transmission gearbox 24, and the like. Sensorscommunicating input through the I/O interface may be used to indicateturbocharger boost pressure, crankshaft position (PIP), enginerotational speed (RPM), wheel speeds (WS1, WS2), vehicle speed (VSS),coolant temperature (ECT), intake manifold pressure (MAP), acceleratorpedal position (PPS), ignition switch position (IGN), throttle valveposition (TP), air temperature (TMP), exhaust gas oxygen (EGO) or otherexhaust gas component concentration or presence, intake air flow (MAF),transmission gear, ratio, or mode, transmission oil temperature (TOT),transmission turbine speed (TS), torque converter bypass clutch 36status (TCC), deceleration or shift mode, for example.

Of course, the control logic may be implemented in software, hardware,or a combination of software and hardware in one or more controllersdepending upon the particular application. When implemented in software,the control logic may be provided in one or more computer-readablestorage devices or media having stored data representing code orinstructions executed by a computer to control the vehicle or itssubsystems. The computer-readable storage devices or media may includeone or more of a number of known physical devices which utilizeelectric, magnetic, and/or optical storage to keep executableinstructions and associated calibration information, operatingvariables, and the like.

An accelerator pedal 48 may be used by the driver of the electrifiedvehicle 10 to provide a demanded torque, power, or drive command topropel the electrified vehicle 10. In general, depressing and releasingthe accelerator pedal 48 generates an accelerator pedal position signalthat may be interpreted by the control unit 40 as a demand for increasedpower or decreased power, respectively. Based at least upon input fromthe accelerator pedal 48, the control unit 40 may command torque fromthe engine 14 and/or the electric machine 18. The control unit 40 alsocontrols the timing of gear shifts within the transmission gearbox 24,as well as engagement or disengagement of the engine disconnect clutch26 and the torque converter bypass clutch 36. Like the engine disconnectclutch 26, the torque converter bypass clutch 36 can be modulated acrossa range between the engaged and the disengaged positions. This producesa variable slip in the torque converter 22 in addition to the variableslip produced by the hydrodynamic coupling between the impeller and theturbine. Alternatively, the torque converter bypass clutch 36 may beoperated as locked or open without using a modulated operating modedepending on the particular application.

To drive the electrified vehicle 10 with the engine 14, the enginedisconnect clutch 26 is at least partially engaged to transfer at leasta portion of the engine torque through the engine disconnect clutch 26to the electric machine 18, and then from the electric machine 18through the torque converter 22 and the transmission gearbox 24. Theelectric machine 18 may assist the engine 14 by providing additionalpower to turn the electric machine shaft 32. This operation mode may bereferred to as a “hybrid mode” or an “electric assist mode.”

To drive the electrified vehicle 10 using the electric machine 18 as thesole power source, the power flow remains the same except the enginedisconnect clutch 26 isolates the engine 14 from the remainder of thepowertrain 12. Combustion in the engine 14 may be disabled or otherwiseturned OFF during this time to conserve fuel. The power electronics (notshown) may convert DC voltage from the battery pack 20 into AC voltageto be used by the electric machine 18. The control unit 40 may commandthe power electronics to convert voltage from the battery pack 20 to anAC voltage provided to the electric machine 18 to provide positive ornegative torque to the electric machine shaft 32. This operation modemay be referred to as an “electric only” or “EV” operation mode.

In any mode of operation, the electric machine 18 may act as a motor andprovide a driving force for the powertrain 12. Alternatively, theelectric machine 18 could act as a generator and convert kinetic energyfrom the electrified vehicle 10 into electric energy to be stored in thebattery pack 20. The electric machine 18 may act as a generator whilethe engine 14 is providing propulsion power for the electrified vehicle10, for example. The electric machine 18 may additionally act as agenerator during times of regenerative braking in which rotationalenergy from spinning the wheels 44 is transferred back through thetransmission gearbox 24 and is converted into electrical energy forstorage in the battery pack 20.

It should be understood that highly schematic depiction of FIG. 1 ismerely exemplary and is not intended to be limiting on this disclosure.Other configurations are additionally or alternatively contemplated, andthe teachings of this disclosure could be applied to any type ofelectrified vehicle having any type of transmission system.

FIG. 2 is a cross-sectional view of a transmission system 16 for anelectrified vehicle, such as the electrified vehicle 10 of FIG. 1 or anyother electrified vehicle that is equipped with an electric machine 18.The transmission system 16 extends along a longitudinal axis A. Thetransmission system 16 may include a front module 60 that is disposedaxially between an engine 14 and a transmission gearbox 24. In thisdisclosure, an axial direction of the transmission system 16 extends inparallel with the longitudinal axis A.

A torque converter 22 is disposed axially between the front module 60and the transmission gearbox 24. The torque converter 22 includes ahousing 61 that defines a periphery that is disposed about thelongitudinal axis A.

The front module 60 includes a housing 62 that at least partiallyencloses the electric machine 18 and an engine disconnect clutch 26. Atransmission housing 64 may substantially enclose the transmissiongearbox 24 and the torque converter 22. In an embodiment, the housing 62and the transmission housing 64 cooperate together to house the electricmachine 18 and the engine disconnect clutch 26. Like the housing 61, thehousing 62 and the transmission housing 64 each define a periphery thatis disposed about the longitudinal axis A.

The housing 62 of the front module 60 may include a first mountingflange 66 and a second mounting flange 68. The first mounting flange 66may interface with a portion of the engine 14, and the second mountingflange 68 may mate with a corresponding mating flange 70 of thetransmission housing 64. The second mounting flange 68 and the matingflange 70 mate along parallel, abutting faces, in an embodiment.

The electric machine 18 may include a rotor 72 received within a stator74. If the electric machine 18 is used as an electric motor, rotatingthe rotor 72 about the longitudinal axis A provides torque foracceleration. Alternatively, if the electric machine 18 is used as agenerator, rotating the rotor 72 about the longitudinal axis A cangenerate electric power. The rotor 72 may rotate in response to a torqueinput from regenerative braking, for example.

The electric machine 18 can generate heat during operation, especiallywhen operating at low speeds and high torques, for example. Thetransmission system 16 may therefore be equipped with a cooling system76 for actively managing the thermal energy levels of the electricmachine 18. The performance capabilities and functionality of theelectric machine 18 may be enhanced by actively managing the thermalenergy levels with the cooling system 76.

Aspects of the cooling system 76 are further illustrated with referenceto FIGS. 3, 4, and 5 . The cooling system 76 may include a spray bar 78.In an embodiment, the spray bar 78 is positioned axially between a rearface 80 of the stator 74 and the housing 61 of the torque converter 22and at a location that is adjacent to a top edge 82 of the stator 74. Inthis example, the top edge 82 coincides with a twelve o'clock positionof the stator 74 (when mounted within the transmission system 16). Thus,in an embodiment, the spray bar 78 is located closer to the twelveo'clock position of the stator 74 than the six o'clock position of thestator 74.

The spray bar 78 may be connected to rear face 80 of stator 74 bypositioning a piloting surface 75 of the spray bar 78 within a groove 77of the stator 74 (see, e.g., FIG. 6 ). However, it is not necessary todirectly connect the spray bar 78 to the rear face 80 of the stator 74.Instead, the spray bar 78 may be suspended within the open space betweenthe stator 74 and the housing 61 of the torque converter 22.

The cooling system 76 may additionally include a feed tube 84, a firstmounting attachment 86, and a second mounting attachment 88. The feedtube 84 may connect between the first mounting attachment 86 and thesecond mounting attachment 88. In an embodiment, the first mountingattachment 86 mounts the feed tube 84 to the housing 62 of the frontmodule 60, and the second mounting attachment 88 mounts the feed tube 84to the spray bar 78. The second mounting attachment 88 may be either anintegral component of the spray bar 78 or a separate component that isattached to the spray bar 78.

In use, coolant C (e.g., oil) that is sourced from the front module 60may be pumped or otherwise communicated within a coolant passage 90 ofthe housing 62 and then into the feed tube 84. The coolant C may travelwithin the feed tube 84 before entering a hollow section 92 of the spraybar 78 via the second mounting attachment 88. In its mounted position,the feed tube 84 may be positioned at a declined angle for directing thecoolant C to the spray bar 78. The coolant C may then be sprayed ormisted through one or more nozzles 94 of the spray bar 78 for coolingthe stator 74. The coolant C may be sprayed by virtue of pressure thatbuilds up within the fluids. The spray of the coolant C may becontinuous so long as pressure remains within the fluid lines. Thecoolant C may then matriculate to the rotor 72 and to the lower half ofthe stator 74 via gravity for cooling additional portions of theelectric machine 18.

Referring now primarily to FIGS. 4-5 , the spray bar 78 may include acurved body 96 that includes a front face 98, a rear face 100, a topsurface 102, and a bottom surface 104. When mounted within thetransmission system 16, the front face 98 faces toward the rear face 80of the stator 74, the rear face 100 faces toward the torque converter22, the top surface 102 faces toward a twelve o'clock position of thetransmission housing 64, and the bottom surface 104 faces toward a sixo'clock position of the transmission housing 64. In an embodiment, thecurved body 96 of the spray bar 78 is crescent shaped and is configuredto cover between about 60 degrees and about 180 degrees (plus/minus 5degrees) of the rear face 80 of the stator 74, as is further discussedbelow.

A plurality of the nozzles 94 may protrude from the front face 98 of thecurved body 96 of the spray bar 78. The size, shape, and number ofnozzles 94 that are provided on the spray bar 78 is design dependent andmay be adjusted in order to provide optimal cooling of the electricmachine 18 while minimizing the coolant flow rate.

The second mounting attachment 88 may extend from or be attached to thetop surface 102 of the curved body 96 of the spray bar 78. The secondmounting attachment 88 acts as an inlet 99 (see FIG. 5 ) for receivingcoolant C within the hollow section 92 of the spray bar 78.

FIG. 7 , with continued reference to FIGS. 2-5 , is a rear view of thestator 74 of the electric machine 18. The stator 74 may include aplurality of back irons 106. Each back iron 106 may be made up oflaminated stacks 108. Windings 110, such as copper windings, may bewound around the laminated stacks 108 of each of the back irons 106.

The spray bar 78 may be positioned relative to the rear face 80 of thestator 74 in order to direct coolant C at specific locations of the rearface 80. In an embodiment, the nozzles 94 of the spray bar 78 arepositioned to direct the coolant C between adjacent back irons 106 ofthe stator 74. The nozzles 94 could be arranged with respect to onlyevery other back iron 106 pair, in another embodiment. In yet anotherembodiment, the nozzles 94 of the spray bar 78 are positioned to directthe coolant C directly onto end windings 112 of the windings 110 of thestator 74 (see FIG. 8 ).

The spray bar 78 may also be positioned to provide for a specificcoverage of the rear face 80 of the stator 74. For example, the spraybar 78 may span an angle α relative to the rear face 80. In anembodiment, the angle α is between 60 degrees and 180 degrees (i.e., thespray bar 78 may cover between 60 degrees and 180 degrees of the rearface 80). The specific value of the angle α is not intended to limitthis disclosure.

FIG. 9 illustrate another exemplary nozzle arrangement that can beemployed by the spray bar 78. In this embodiment, the spray bar 78includes a plurality of primary nozzles 94A and a plurality of secondarynozzles 94B. The primary nozzles 94A may be positioned to direct coolantC between adjacent back irons 106 of the stator 74, and the secondarynozzles 94B may be positioned to direct the coolant C directly onto theend windings 112 of the windings 110 of the stator 74.

In an embodiment, the primary nozzles 94A include orifices having afirst diameter D1, and the secondary nozzles 94B include orifices havinga second diameter D2. The second diameter D2 may be a smaller diameterthan the first diameter D1.

The exemplary transmission systems of this disclosure utilize coolingsystems that are positioned to occupy the typically unused space betweenthe stator and torque converter of the transmission system.Implementation of the proposed cooling systems therefore requiresminimal changes to existing electric machine and torque converterarchitecture. Spray bars of the cooling systems are configured tospray/mist coolant onto the rear face of the stator and then rely ongravity for cooling the remaining portions of the electric machine.Actively cooling the stator in this manner allows the electric machineto operate at higher torques and speeds, thereby increasing itsperformance capabilities.

Although the different non-limiting embodiments are illustrated ashaving specific components or steps, the embodiments of this disclosureare not limited to those particular combinations. It is possible to usesome of the components or features from any of the non-limitingembodiments in combination with features or components from any of theother non-limiting embodiments.

It should be understood that like reference numerals identifycorresponding or similar elements throughout the several drawings. Itshould be understood that although a particular component arrangement isdisclosed and illustrated in these exemplary embodiments, otherarrangements could also benefit from the teachings of this disclosure.

The foregoing description shall be interpreted as illustrative and notin any limiting sense. A worker of ordinary skill in the art wouldunderstand that certain modifications could come within the scope ofthis disclosure. For these reasons, the following claims should bestudied to determine the true scope and content of this disclosure.

What is claimed is:
 1. A transmission system, comprising: an electricmachine including a rotor and a stator, wherein the stator includes aplurality of sets of laminated stacks; and a spray bar configured todirect a coolant between a first set and a second set of the pluralityof sets of the laminated stacks.
 2. The transmission system as recitedin claim 1, wherein each set of the laminated stacks is part of a backiron of the stator.
 3. The transmission system as recited in claim 1,comprising a front module that at least partially houses the electricmachine, a transmission gearbox aft of the front module, and a torqueconverter located axially between the front module and the transmissiongearbox.
 4. The transmission system as recited in claim 3, comprising afeed tube connected to the front module by a first mounting attachmentand connected to the spray bar by a second mounting attachment.
 5. Thetransmission system as recited in claim 1, wherein the spray barincludes a crescent shaped body.
 6. The transmission system as recitedin claim 1, wherein the spray bar includes a curved body that coversbetween 60 degrees and 180 degrees of a face of the stator.
 7. Thetransmission system as recited in claim 1, wherein the spray bar islocated near a top edge of the stator, and the top edge coincides with atwelve o'clock position of the stator.
 8. The transmission system asrecited in claim 1, wherein the spray bar includes a plurality ofnozzles.
 9. The transmission system as recited in claim 8, wherein afirst nozzle of the plurality of nozzles is configured to direct acoolant between the first set and the second set of the laminated stacksand a second nozzle of the plurality of nozzles is configured to directthe coolant onto end windings of the stator.
 10. The transmission systemas recited in claim 9, wherein the first nozzle includes a first orificehaving a first diameter and the second nozzle includes a second orificehaving a second diameter, wherein the first diameter includes adifferent diameter than the second diameter.
 11. The transmission systemas recited in claim 1, wherein the spray bar includes a piloting surfacereceived within a groove of the stator.
 12. The transmission system asrecited in claim 1, wherein the spray bar is suspended within an openspace defined between the stator and a torque converter housing.
 13. Thetransmission system as recited in claim 1, wherein the coolant is oil.14. The transmission system as recited in claim 1, wherein thetransmission system is configured such that the coolant matriculates tothe rotor from the stator via gravity.
 15. The transmission system asrecited in claim 1, wherein the spray bar includes a curved body havinga front face that faces toward a rear face of the stator and a rear facethat faces toward a torque converter, and further wherein a plurality ofnozzles protrude from the front face and are configured for spraying thecoolant onto the rear face of the stator.
 16. An electrified vehicle,comprising: a front module at least partially housing an electricmachine; a transmission gearbox aft of the front module; a torqueconverter located between the front module and the transmission gearbox;and a spray bar configured to direct a coolant between a first set and asecond set of a plurality of sets of laminated stacks of a stator of theelectric machine.
 17. The electrified vehicle as recited in claim 16,wherein the spray bar includes a curved body having a front face thatfaces toward a rear face of the stator and a rear face that faces towardthe torque converter.
 18. The electrified vehicle as recited in claim17, comprising a plurality of nozzles that protrude from the front faceof the curved body.
 19. The electrified vehicle as recited in claim 17,wherein the curved body is crescent shaped.
 20. A transmission system,comprising: an electric machine including a rotor and a stator, whereinthe stator includes a plurality of sets of laminated stacks; a spray barconfigured to direct a coolant between a first set and a second set ofthe plurality of sets of the laminated stacks; a front module that atleast partially houses the electric machine, a transmission gearbox aftof the front module, and a torque converter located axially between thefront module and the transmission gearbox; and a feed tube connected tothe front module by a first mounting attachment and connected to thespray bar by a second mounting attachment, wherein the feed tube is influid communication with a coolant passage formed in the front module atthe first mounting attachment and is in fluid communication with ahollow section of the spray bar at the second mounting attachment.